1. Field of the Invention
The present invention relates to surgical tamps and more specifically to a bone tamp apparatus.
2. Description of the Related Art
Bone tamps provide surgeons a valuable option for the repair of compression bone fractures. The tibial plateau, as one example, is vulnerable to being fractured and depressed due to varus or valgus stress and/or axial compression. Bone tamps are used to reposition the fractured and displaced bone into a natural position. Prior art bone tamps are typically simple solid straight instruments that have a cylindrical shape and a distal face or tamping surface with a fixed quantity of surface area for the displacing of bone tissue. The tamping surfaces of prior art bone tamps are solid and have flat disk type shapes without openings or breaks in the tamping surfaces.
In one current surgical procedure as an example, access to the tibia is created by making a surgical incision in a generally anterior and medial position on the proximal aspect of the tibia, below the level of the tibial plateau fracture as shown in FIG. 1 (prior art). An opening is then created in the hard, outer, cortical bone in line with this incision in order to provide access for a bone tamp. This opening in the cortical bone is typically created by making multiple drill holes in a circular shape and then connecting these holes through the use of an osteotome and a mallet. After removing this “cortical window” in the bone, a tamp is inserted through the window into the soft, inner cancellous bone where it is then positioned for treating the tibia fracture. A mallet is used to tap the proximal terminal end and drive the distal tamping face of the tamp into the fracture. The tamp repositions the displaced bone material into a natural position.
When the tamping of the displaced bone material is completed, the tamp is withdrawn. The path taken by tamp to return the displaced bone to the natural position leaves a void in the bone that is then backfilled using a bone graft or bone graft substitute such as various, commercially available bone cements. The backfilling procedure places the bone graft into the void by injecting the material through a large bore needle or cannula. Tamps may also be used to compress the backfilled bone graft to ensure the structural integrity of the graft. The term bone graft as defined herein includes a bone graft, bone graft substitute, bone cement or any another material approved for use as a bone graft. The term tamping surface as defined herein is the distal terminal end or face of the tamp that directly contacts the cancellous bone as described above to displace that bone and/or compress the bone graft.
The simple prior art bone tamp is limited in its ability to perform additional functions during a surgical procedure. For example, the tamp requires a large bone window and skin incision. This causes significant bleeding and soft tissue trauma. The placement of the tamp directly below the fracture site can also be difficult and typically requires several trial and error attempts each of which leaves a path of bone void which needs to be backfilled at the end of the procedure. The application of the prior art tamp to many common fractures can also require an excessive amount of time due to the relatively small surface of the face of the tamp relative to the wider surface of the fracture. Effective backfilling can also be compromised by the fact that the prior art tamps require a two step process in which the tamp is removed and then the bone graft is injected into the void. Problems occur because upon the removal of the tamp from the bone, blood begins to accumulate in the void from the tamp that prevents an optimal graft integration with the native bone.
While cannulas have expandable structures for different functions, such as those in U.S. Pat. No. 6,632,197 to Lyon that is incorporated herein by reference and made a part of this disclosure, heretofore bone tamps have neither had apertures aligned with the longitudinal axis or structures that increase the tamping surface area. Tamps have not had apertures for receiving a guide wire which can perform functions such as the scouting out and aligning of the ultimate trajectory of the tamp as well as the introduction of backfill.
The repair of certain bone fractures, such as those of the tibial plateau can benefit from a tamp apparatus that is not solely limited to tamping. A tamp apparatus is needed that combines a tamp and a cannula that defines a through hole or aperture that is aligned with a longitudinal axis of the tamp. The aperture advantageously provides a passageway for a guide wire such that the tamp apparatus can be slid over an accurately pre-positioned guide wire that is placed beneath the depressed fragment of bone. The guide wire can then be used to direct the tamp to the desired point and angle for application. In addition, the aperture allows for the subsequent injection of bone graft through the aperture of the cannula as the tamp is withdrawn from the fracture site. Further, a tamp apparatus is needed that has a narrow cross-section that can be selectively expanded to increase the tamping surface.